|
Articles
Introduction
Camcorder Survival Kit
Maintenance
Key With Metal Tape
Avoiding Head Clogs
Ikegami/Avid's Disk Recording System
Matchmaker, Matchmaker
A Call for Uniformity
The Ultimate Camera Standard
Looking Your Best
Video Head Evaluations
Sony Investigates Betacam Camcorder Headwear Problems |
Maintenance Key With Metal Tape
By Mark Bell
Note -
Click here for Camera and VTR
maintenance training streaming video
If you've been in the
industry for more than ten years, you can appreciate how far the medium has
progressed. As we have advanced ourselves, the manufacturers have advanced
us with the absolute miracles of technology. But sometimes, with those
miracles, there comes a learning curve.
It has been discovered that metal tape use vs. oxide product will double the
life of tape heads. This good news also comes with some not-so-good news.
A compound that may be a product or by-product of the lubrication used to
facilitate metal tape travel "slippage" has been thought to be the cause of
a situation similar to a head clog on small format camcorders. Identified by
Roger Macie, of Dedham, MA, as "baked-on" residue, this situation has caused
"clog-type" characteristics that do not disappear with standard cleaning
methods.
This advisory is not a cause for alarm as much as a call for facility
maintenance people to learn a different regimen for maintenance of the SDH
series (small head diameter) VCRs. Microscopic observation of the head
followed by cautious use of a head-cleaning cassette is recommended for
dealing with this situation. Be cautious, however. The tip penetration of
the smaller diameter heads and expense of head replacement mandates more
than casual use of an abrasive head cleaning cassette. If you don't know,
leave it to a pro. Your head is a terrible thing to waste.
Macie's Find
Roger Macie, a veteran
maintenance technician, recently gave notice to Ikegami and Sony that he was
seeing a consistent pattern of a compound amassing on the heads of SDH
series machines.
Macie discovered the characteristic during a microscopic examination of the
heads that were performing consistent to a VCR with a clogged head, even
after a rigorous cleaning.
"Clients were coming in with badly recorded tapes with one or two heads
apparently clogged," Macie says. "Their original perception was a chroma
breakup, of sorts, that I came to see as that, and a distortion in the RF
envelope."
Conventional cleaning methods such as head cleaner and/or alcohol and a
clean wipe are not effective in removing the compound.
"The only way I could effectively clean this compound off the head was to
use an abrasive cleaning tape," Macie adds. "Even then, some heads do not
clean off enough to totally eliminate the marks I saw under the microscope,
and warrant a second or third 5-second pass with the cleaning tapes: the
stuff was really on there!"
One thing that may be a bit scary about this characteristic is that there is
not always an RF warning when there is a "baking" condition. There is not a
large deficiency of RF, which is the keying point of RF warning signals.
There is, however, distortion of RF envelope that will similarly distort
your video.
Manufacturers Response
Tom Calabro, Executive VP and
Director of Engineering for Ikegami, US, is aware of Roger's discovery, and
expressed confidence that proper maintenance was the key.
This is certainly something that has to be dealt with. "It's a minor
disadvantage, but can be dealt with by performing proper maintenance, just
like changing belts. Those cleaning tapes that you used to keep on the
shelf? You'll need to use them now."
Dan Smith, Senior Technical Services Representative from Sony's Alabama
Media Plant, is also familiar with the challenge of the "baked-on" compound.
"The drum spins faster in the (SDH) product. And the contour of the surface
of the tape is different. These factors alone may lead to a situation that
warrants a more frequent cleaning of the heads," he says. "We are always
looking to change or modify our products to make them better, and perhaps a
cleaning every 40 to 50 hours with one of our micro-abrasive cleaning
cassettes is a characteristic of a newer more superior technology.
Reinforcing Smith's opinion, a bulletin from Sony Electronics Recording
Media Productions Group says the following: "In order to remove this build
up, Sony recommends a complete cleaning every 20 hours of tape time. Sony
also recommends that a head-cleaning cassette be used every second cleaning
(40-50 hours) FOR ONLY FIVE SECONDS." Sony has also issued a service
bulletin for this "build-up" characteristic.
Roger has had different experiences with different build ups, and has had to
run an abrasive tape for as long as 60 seconds to remove excess mass on some
heads. This long time period is not recommended without simultaneous
microscopic monitoring. Leave it to a pro with the tools Macie states:
"Checking the CTDM (compressed time division multiplex) signal while playing
back the last 15 or 20 seconds of a recorded tape is (an accurate status
indicator}. Any distortion, or breakup, in this signal would warrant cause
for concern, and perhaps some cleaning on the spot. It is essential that the
last 15 seconds be played back, and not too much less, as you can also
control track discrepancies, another symptom of the condition. These are not
always apparent with a quicker playback of 5 seconds for instance.
What's the saying? "There is no such thing as a free lunch." Here we have
this great gear that'll do it all with such nice quality, but it's not free.
We are saving money on one hand, but having to spend some of the savings on
maintenance. This "baking" characteristic, while not apparent on CDH VCRs,
is as much a part of the state-of-the-art SDH VCRs as FM audio. If you are
getting the highest quality out of the product and saving the head wear via
metal recording media, you'll also have to change your habits and perform
frequent cleaning.
A thought worth some merit is to use an SDH camcorder with a separate CDH
series VCR for location production shoots when the characteristics of such
work allow for the larger package. This lessens the chance of the "keeper"
being affected by the baking phenomenon.
Other principles of consideration have pointed toward tape storage. Sony
Corporations Recording Media Products Group published a comprehensive
advisory in January of 1991. MPG Technical Report Volume 6 can educate the
reader on "Archival Stability." The report is very well written and details
and not-so technical points.
The MPG Tech report, obviously, would not be able to address newer series of
tapes like the BCT-D, BCT-Ma, and UVWT-Ma tapes which are superior to those
of previous years. Sony and other manufacturers will continue to improve
their technology, and it is certain, as long as we are in a technology that
depends on heads and tapes, we will encounter the effects inherent to the
techniques.
John Matarazzo, National Technical Services Manager for Sony's Recording
Media Group agrees. "Improvements in lubricants and binding systems produce
conditions that will improve the vulnerability of tape."
Being more specific, Matarazzo says, "The new BCT-Ma series has improved
cross-linking (mechanical composition) and has systems that contribute to a
reduction in surface debris."
It's an age of new technologies that require different methods of
performance and maintenance than the technologies of the past. Field color
shifts, multi-frame distortions and repetitive dropouts do not necessarily
indicate situations that warrant extensive repair. The cause might be from
manageable characteristics that warrant attention by different methods of,
and more frequent, cleanings.
Joseph Tibensky, Director of Marketing for the Recording Media Products
Group, adds, "During the normal evolution of any product, we try to make as
many improvements as possible. Sony BCT-Ma series between Betacam SP
cassettes, which have now been on the market for two full years, feature
improved runnability, cleanliness and durability beyond that of the previous
BCT-M series. Since the introduction of this formulation, and that of the
similar Broadcast Master formulation for D-2 cassettes and HMPX Hi8
formulation two years ago, the Sony Professional Media Division has been
enjoying the highest level of professional video cassette product
reliability in our history." |
broadcastvideo.com
NewPro Video
ProSource
Freelance Page
Net Police
ENG Safety
Pro Finder |
